The Centers for Disease Control and Prevention has issued an alert for Rocky Mountain Spotted Fever after at least five U.S. residents contracted the disease since July after traveling to Mexico.
The health agency says that although the disease is usually associated with tick-borne transmission, most of those infected do not remember being bitten.
“RMSF is endemic in northern Mexico and areas of the southwestern United States,” the CDC said.
All patients had traveled to, or previously lived in, the Tecate area of the Mexican state of Baja California, within two weeks of showing symptoms.
All five US cases were identified in southern California and all but one of the patients were minors. Three of the people who contracted the disease died, according to the CDC.
The agency advises people to check themselves, as well as their pets and children, for ticks.
The CDC urges health care providers to administer the antibiotic Doxycycline and for physicians to consider a diagnosis of RMSF in patients who have recently traveled to northern Mexico if they have “unexplained severe febrile illness.
“Consider starting Doxycycline based on presumptive clinical and epidemiologic findings, and do not delay treatment while awaiting the results of a confirmatory laboratory test,” the CDC said. added, “Early treatment with Doxycycline saves lives.”